This invention relates generally to methods and apparatus for resecting bones and more particularly to methods and apparatus for resecting bones through a minimally invasive incision.
Current trends in joint replacement surgery suggest that smaller incision size can lead to faster recovery, improved quadriceps function and increased patient satisfaction. Joint replacement surgery typically requires bone resection in preparation for an implant. Traditional instrumentation for orthopaedic implants is designed around an oscillating saw blade used to resect the bone. Cutting blocks, pins and alignment towers place and hold the saw blade in the proper orientation. However, these blocks are large and require a large incision.
When a patient undergoes total knee replacement (TKR) it is common for the patient to stay in the hospital for one to two weeks. Rehabilitation therapy lasts months and most patients do not fully recover for years. Some patients never fully recover. This recovery process poses a substantial psychological and financial strain on TKR patients. Many patients are in the latter years of their lives and this recovery period represents a significant portion of the remaining years.
Many orthopaedic companies offer a “minimally invasive” knee replacement. The claim “minimally invasive,” as used with regard to knee replacements, usually refers to an incision of six to ten cm. This is a great improvement over the twenty to thirty cm incision of the past. Peer reviewed articles have already demonstrated the faster recovery, shorter hospital stays, and improved patient satisfaction resulting form using minimally invasive knee replacements. The logical progression would be to decrease the incision size even further. However, the common constraint is a saw blade, the block required to capture that blade and the pins required to secure the block.
The disclosed method uses a saw guided along holes formed in the bone to prepare a bone to receive an implant. Thus, rather than requiring an incision sized to permit insertion of a rotating or reciprocating saw blade, tower and block, the disclosed method requires small incisions to facilitate forming holes, into which pins may be inserted, and guiding a wire saw along the hole or the pins.
One aspect of the disclosure aligns two pins inside the bone to be resected such that those pins describe a surface. A wire cutting saw is then tensed between the pins to resect bone along that surface. This bone cutting method may be accomplished through a true arthroscopic incision (<1 cm).
Thus, the disclosed device and method enables TKR without a large skin incision. Also the method enables the preservation of musculature, ligaments, tendons, nerves and the blood supply. By allowing the surgeon to prepare the bone arthroscopically, the method facilitates reduced tourniquet time, reduced anesthetic requirements, and a reduction in the risk of infection.
According to one aspect of the disclosure a guide system for resecting a bone through incisions of the type utilized for arthroscopic procedures is provided. The guide system comprises a first alignment pin, a second alignment pin and a wire saw. The first alignment pin is configured to be inserted through one of the incisions into a bone in a first orientation. The second alignment pin is configured to be inserted through one of the incisions into the bone in a second orientation. The first alignment pin and the second alignment pin are configured and oriented to define a resection surface of reference through which the bone is to be resected and the wire saw is configured to be inserted through at least one of the incisions to be guided by the first and second alignment pins while being moved to resect the bone.
According to another aspect of the disclosure, the apparatus may further comprise a guide block formed to include a first guide hole extending through the block. The first guide hole is sized to receive a drill sized to form a hole in the bone sized to receive the first alignment pin. The first alignment pin has a length sufficient that the first alignment pin extends completely through the bone with one tip extending beyond the bone on a first side and the second tip extending beyond the bone on the opposite side and into the first guide hole when the guide block is positioned on the opposite side of the bone. The guide block may be formed to include a first saw guide and a second saw guide to guide the saw along the resection plane of reference when the saw is received in the saw guides.
According to yet another aspect of the disclosure the guide pin and wire saw apparatus may also include a saw driver configured to be guided by the first pin through the bone and to drive the saw guided by the saw driver and the second alignment pin through the bone.
According to yet another aspect of the disclosure, the guide pin and wire saw apparatus may also include a saw frame having a shaft adapted to be coupled to an oscillator, a finger coupled to the shaft at one end for movement between a retracted position wherein a second end of the finger is adjacent the shaft and an extended position wherein the second end is displaced from the shaft. The wire saw is coupled to the shaft and the finger adjacent the second end to be tensioned between the shaft and the second finger when the second finger is in the extended position.
According to yet another aspect of the disclosure, a method of resecting a bone of a patient comprises an incising step, a forming step an inserting step and a resecting step. The incising step includes incising the skin and underlying tissue at a first point overlying the bone with an incision having a length less than six centimeters. The forming step includes forming a hole through the bone with an instrument inserted through the incision. The inserting step includes inserting a saw through the incision. The resecting step includes resecting the bone along the formed hole with the inserted saw.
According to still another aspect of the disclosure, an apparatus for resecting a bone comprises a wire saw and a saw driver. The saw driver includes a shaft adapted to be driven by a rotary drill to rotate about an axis. The saw driver also includes a body coupled at a first end to the shaft to be rotated thereby about the axis. The body includes a second end formed to include teeth adapted to cut through the bone and a wall extending between the first end and the second end. The wall is formed to include a driver surface for engaging the wire saw and driving the same during rotation of the body.
Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.
Corresponding reference characters indicate corresponding parts throughout the several views. Like reference characters tend to indicate like parts throughout the several views.